#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------


int N,K;
ll A[101010];
ll S[303030];

int ok(ll v) {
	vector<int> C;
	C.push_back(0);
	int cur=0;
	while(cur<3*N) {
		int nex=lower_bound(S+cur,S+3*N+2,S[cur]+v)-S;
		if(C.size()>=K&&nex-C[C.size()-K]<=N) return 1;
		C.push_back(nex);
		cur=nex;
		
	}
	return 0;
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>K;
	FOR(i,N) cin>>A[i];
	FOR(i,3*N) S[i+1]=S[i]+A[i%N];
	S[3*N+1]=1LL<<60;
	
	ll ret=0;
	for(i=50;i>=0;i--) if(ok(ret+(1LL<<i))) ret+=1LL<<i;
	cout<<ret<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}